ADSL2+ and min SNR

I think we should all be very clear that reduction of SNR (especially on ADSL2+) is not something that can be done 'on demand' from Wholesale, I'm sorry if you have been given the impression it can. By your own admission you don't have a fault but clearly I'd like us to come to a reasonable understanding and I'd like your issue to be properly understood and investigated. You have chosen to take part in the ADSL2+ trial and I suggest this conversation would now be better conducted in that arena rather than your becoming frustrated at our support staff who are following our standard processes.http://community.plus.net/forum/index.php/board,62.0.html

Moving from ADSL with min SNR 9dB interleaved to ADSL2+ with min SNR 12dB no iterleaving has slightly reduced download performance. Is this to be expected?Are you saying min SNR behaves differently on ADSL2+ and people 3km + from the DSLAM can expect a reduction in download speeds.The change from 9dB to 12dB wasn't at my request so why was it done if it is so difficult to get it reversed?Some information on what can be expected with ADSL2+ and SNR would be helpful.According to the Kitz site I should have expected a slight improvement in download speed.

Re: ADSL2+ and min SNR

Hi fredor your snr is controlled by the DLM not Plusnet or BTW in might be possible to "tweaK" your SNR Things do change when you move from MAX to ADSL2+ for one thing your Line Attenuation increasesThe first thing you should do is post your router stats and i am sure the "experts" here will try and help you out

Re: ADSL2+ and min SNR

Hi ctech500,Thanks for your interest.SNR may well be controlled by DLM but as I understand it has to be requested though PlusNet.Yes I can tweak my SNR and I did this regularly when on ADSL at a min SNR of 6dB. I had the min SNR increased to 9dB and this avoided tweaking.Now I am on ADSL2+ with a min SNR of 12dB which I can tweak downwards but the problem is if the system reboots for any reason sync speed is lower and the IP Profife is lowered.You are then stuck with lower download speeds until BT adjust your IP Profile.A high sync speed is irrelevant with a low IP Profile.Things did change when moving to ADSL2+.Attenuation increased from 41dB to 43.5dB.Interleaving was turned off and min SNR was increased to 12dB.Upspeeds are excellent near to the max possible.Current status is as follows:-Status: ShowtimeRetrain Reason: 8000Channel: FAST, Upstream rate = 1123 Kbps, Downstream rate = 6259 KbpsLink Power State: L0Mode: ADSL2+Channel: FastTrellis: U:ON /D:ONLine Status: No DefectTraining Status: Showtime Down UpSNR (dB): 11.6 6.2Attn(dB): 43.5 21.3Pwr(dBm): 0.0 13.0Max(Kbps): 7264 1136Rate (Kbps): 6259 1123IP Profile is 4500kbpsDownload speed 4078kbpsThese are worse than achieved with ADSL except for upspeeds of course.

Re: ADSL2+ and min SNR

okin my experience the best thing is to have interleaving set to auto. if you PM jamesh he will do that for you.takes about 24 hours Turning interleaving off will increase errors and DLM will raise the SNR to ensure stability. this may also effect your sync speedModerator's note by David (spraxyt): removed large amount of white space to improve thread readability.

Re: ADSL2+ and min SNR

SNR may well be controlled by DLM but as I understand it has to be requested though PlusNet.Things did change when moving to ADSL2+.Attenuation increased from 41dB to 43.5dB.Interleaving was turned off and min SNR was increased to 12dB.

No, the DLM controls the target SNR margin based on line conditions; this applied also on ADSL but the changes on ADSL2+ are more aggressively applied. There is ample evidence in this forum that automatic changes do happen, though the process can take a couple of weeks.An increase in attenuation is to be expected on ADSL2+ because higher frequencies are brought into use. Attenuation at these higher frequencies is higher so the weighted average reported by the router is increased. The change you saw is normal.ADSL2+ seems able to hang onto connections with lower SNR margins than ADSL. In fact the minimum target in its armoury is 3dB. It is possible the DLM will try 6dB and even 3dB on your line. If these generate a high number of errors the target will increase again within a day or so.

Re: ADSL2+ and min SNR

Now I am on ADSL2+ with a min SNR of 12dB which I can tweak downwards but the problem is if the system reboots for any reason sync speed is lower and the IP Profife is lowered.

if you've got netgear you might want to check out the unoffical DGteam fimwares as these have snr tweaks that last a reboot but most defo a resync http://dgteam.ilbello.com/tho you most likely all ready know that tweaking your margin your self might send the DLM in to shock and you end up with a even higher default noise margin.i know you have a diff thread some where but at this time of the morning ive lost thee will to navigate the forumif you havent all ready then i would surrgest trying to run http://www.vwlowen.co.uk/internet/files.htm or http://www.kitz.co.uk/routers/DMTv8.htmon your router and see a more detailed picture of whats going on

Re: ADSL2+ and min SNR

you most likely all ready know that tweaking your margin your self might send the DLM in to shock and you end up with a even higher default noise margin.

DLM dose tend to "wobble" when tweaking the margin, I find it best to tweak it slowly I had a very high margin in the early days of the trial and i was beginning to think that DLM had "locked" on to the figure.I also agree that anyone with a Netgear router ie DG834xx should use the DGteam Firmware it can work wonders with this pesky DLM system

Re: ADSL2+ and min SNR

With the 12dB SNR on Fastpath, errored seconds are 0-6/15mins. Over the 24 hours, they will be maybe 200 or higher but most of these are when I am offline.

Quote from: ASBO

if you've got netgear you might want to check out the unoffical DGteam fimwares as these have snr tweaks that last a reboot but most defo a resync http://dgteam.ilbello.com/tho you most likely all ready know that tweaking your margin your self might send the DLM in to shock and you end up with a even higher default noise margin.

I do have a Netgear DG834PN so thanks for the info on DGteam. It should be interesting.I am going to try interleaving which in the past reduced errored seconds to virtually zero at 9dB on ADSL1.I mainly run linux but I have a Windows Vista system and gave the DTM tool a quick try but it didn't recognize the modem.

Re: ADSL2+ and min SNR

No idea what the target SNR is on my line at the moment and I'm not rebooting in case it isn't 3dB With interleaving on my ine is perfectly stable, don't think I'd want to try it without. Interleaving is normally the first tool the DLM uses to try and improve stability, then the target SNR and last it uses banded profiles to cap the speed. I think I agree that switching interleaving on would be the best option and assuming it stays stable it then wouldn't take long to drop to a 9dB inteleaved profile. While we can change the interleaving status we have very little control over the target SNR. Even when we do change it, it doesn't get capped at that rate and can easily change again.ADSL Statistics Mode: ADSL2 Line Coding: Trellis On Status: No Defect

Re: ADSL2+ and min SNR

According to jameseh, interleaving is now turned on although my Netgear DG834PN still shows channel = fast.The errored seconds reported have reduced considerably and I now get 24ES in 19 hours so I guess interleaving must be on.It will be interesting to see what happens from now on.